Simulation of the metabolism of amino acids postulated to be transmitters in the central nervous system viz. glutamic acid, aspartic acid and gamma-aminobutyric acid, will be carried out to match data generated in tracer experiments using specifically labeled precursors, e.g. acetate, propionate and glucose labeled in specific positions with carbon-14. Other data using tritiated acetate as precursor will be considered. The computer simulation model for mouse brain developed by van den Berg and Garfinkel will be modified and expanded to fit data from our laboratory as well as from the literature on the labeling of the above amino acids in brain after administration of labeled precursors.